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Re: [PATCH v3] migration: Count new_dirty instead of real_dirty
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [PATCH v3] migration: Count new_dirty instead of real_dirty |
Date: |
Fri, 3 Jul 2020 15:20:13 +0100 |
User-agent: |
Mutt/1.14.5 (2020-06-23) |
* Keqian Zhu (zhukeqian1@huawei.com) wrote:
> real_dirty_pages becomes equal to total ram size after dirty log sync
> in ram_init_bitmaps, the reason is that the bitmap of ramblock is
> initialized to be all set, so old path counts them as "real dirty" at
> beginning.
>
> This causes wrong dirty rate and false positive throttling.
>
> Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
OK,
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
and queued.
you might still want to look at migration_trigger_thrtottle and see if
you can stop the throttling if in the RAM bulk stage.
> ---
> Changelog:
>
> v3:
> - Address Dave's comments.
>
> v2:
> - Use new_dirty_pages instead of accu_dirty_pages.
> - Adjust commit messages.
> ---
> include/exec/ram_addr.h | 5 +----
> migration/ram.c | 8 +++++---
> 2 files changed, 6 insertions(+), 7 deletions(-)
>
> diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h
> index 7b5c24e928..3ef729a23c 100644
> --- a/include/exec/ram_addr.h
> +++ b/include/exec/ram_addr.h
> @@ -442,8 +442,7 @@ static inline void
> cpu_physical_memory_clear_dirty_range(ram_addr_t start,
> static inline
> uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock *rb,
> ram_addr_t start,
> - ram_addr_t length,
> - uint64_t *real_dirty_pages)
> + ram_addr_t length)
> {
> ram_addr_t addr;
> unsigned long word = BIT_WORD((start + rb->offset) >> TARGET_PAGE_BITS);
> @@ -469,7 +468,6 @@ uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock
> *rb,
> if (src[idx][offset]) {
> unsigned long bits = atomic_xchg(&src[idx][offset], 0);
> unsigned long new_dirty;
> - *real_dirty_pages += ctpopl(bits);
> new_dirty = ~dest[k];
> dest[k] |= bits;
> new_dirty &= bits;
> @@ -502,7 +500,6 @@ uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock
> *rb,
> start + addr + offset,
> TARGET_PAGE_SIZE,
> DIRTY_MEMORY_MIGRATION)) {
> - *real_dirty_pages += 1;
> long k = (start + addr) >> TARGET_PAGE_BITS;
> if (!test_and_set_bit(k, dest)) {
> num_dirty++;
> diff --git a/migration/ram.c b/migration/ram.c
> index 069b6e30bc..5554a7d2d8 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -859,9 +859,11 @@ static inline bool migration_bitmap_clear_dirty(RAMState
> *rs,
> /* Called with RCU critical section */
> static void ramblock_sync_dirty_bitmap(RAMState *rs, RAMBlock *rb)
> {
> - rs->migration_dirty_pages +=
> - cpu_physical_memory_sync_dirty_bitmap(rb, 0, rb->used_length,
> - &rs->num_dirty_pages_period);
> + uint64_t new_dirty_pages =
> + cpu_physical_memory_sync_dirty_bitmap(rb, 0, rb->used_length);
> +
> + rs->migration_dirty_pages += new_dirty_pages;
> + rs->num_dirty_pages_period += new_dirty_pages;
> }
>
> /**
> --
> 2.19.1
>
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
- Re: [PATCH v3] migration: Count new_dirty instead of real_dirty,
Dr. David Alan Gilbert <=